Chordate Zoology - textbook - Y. V. Tsaryk - 2013

Chapter 4. DIVISION GNATHOSTOMATA, or ECTOBRANCHIATA. SUPERCLASS PISCES

4.2. CLASS BONY FISHES OSTEICHTHYES

4.2.3. Systematics of the Class of Bony Fishes and Characteristics of Representatives of Individual Orders

4.2.3.3. Group Teleost Fishes Teleostei

4.2.3.3.8. Superorder Batrachoidomorpha

A small group of Fishes adapted to Life in the coastal zone; some species have secondarily transitioned to a pelagic or deep-sea lifestyle. The pelvic fins are located on the throat and may fuse into a sucker or be reduced. The swim bladder is closed.

Order Batrachoidiformes (Toadfishes). Sluggish bottom-dwelling fishes up to 20-30 cm in length with a large, flattened HEAD. They live among Algae in coastal areas of warm seas. They feed on invertebrates and small fish. They are solitary. Using their swim bladder, they produce loud sounds (over 100 decibels) to signal that their territory on the seabed is occupied. There are about 50 species in total.

Order Lophiiformes (Anglerfishes). The order comprises 220-250 species of predatory marine fishes. One or several rays of the dorsal fin are shifted to the front of the head, transforming into a movable rod with a bulbous tip (sometimes with a bioluminescent organ) called the illicium; by moving it, the fish lure prey. In many species, the pectoral fins are used for crawling; they possess a sturdy Skeleton and strong Muscles. In bottom-dwelling species, the body is dorsoventrally flattened. Numerous Skin Appendages and spines, along with the ability of some species to change color, facilitate camouflage. They lie in wait for prey on the seabed. They feed on various fishes, crabs, and cephalopods. About 120 species live in the midwater zone at depths of 1-2 km or more. Some deep-sea species are known for dwarf males (5-15 times smaller than females) that can attach and fuse to the female with their Mouth, becoming true ectoparasites: their digestive tract and Sensory Organs degenerate, and a connection with the female's bloodstream is established. This male parasitism likely evolved due to the low probability of finding a mate, as species of this order are sluggish, solitary animals living at great depths.